1. Field of the Invention
This invention relates to improvements to hub-lock system for vehicles which are convertible between two-wheel and four-wheel drive, the hub lock system being actuated automatically or manually, and the manual portion of the system having a minimum number of operating parts for reliable operation.
2. Background of the Invention
Vehicles having four-wheel drive capability that are designed for on-road and off-road use typically provide optional engagement/disengagement of two of the four wheels. The wheels to be disengaged generally are provided with a drive line from a transfer case to the wheels. For on-road use and to avoid unnecessary energy consumption, and wearing of out-of-service drive line components, a first disconnect system disconnects the propeller shaft from the transfer case and a second disconnect system disconnects the axles from the wheels. This latter disconnect system is the hub lock system of the present invention.
Originally hub lock systems were manually actuated. A driver-operator would stop the vehicle, engage the transfer case disconnect system and then manually turn a dial located in each wheel hub to activate the hub lock. Subsequently, mechanism was developed to automatically activate the hub locks. Several versions of automatically actuated hub locks have been developed. One version relies on cam actuation whereby a cam mechanism is powered by rotation of the axles. Other systems involve pressure, or vacuum, actuated systems to shift a clutch member into position to provide interlock between the drive axle and the wheel, or to shift into a disconnected position. Further examples of automatic connect/disconnect systems include electromagnetic devices which also provide shifting of clutch members into connect or disconnect states.
Many four-wheel drive enthusiasts want both the convenience of automatic engagement/disengagement and the security of manual engagement. Prior patents illustrating hub lock systems having both automatic and manual actuation are U.S. Pat. Nos. 5,353,890 and 5,520,272.
Although the basic concept of having a hub lock system which may be automatically actuated from a remote location by a vehicle operator with a manual override thus is known generally, previous devices often have had more complex structure and more parts than may he desirable for positive operation and reliability from a maintenance standpoint. Such prior devices also may have been more expensive to manufacture due to their complexity.